The invention relates to a fuel injection pump for internal combustion engines. More particularly, the invention relates to a fuel injection pump to be used in a Diesel engine and including a simultaneously rotating and reciprocating pressurizing piston. The pump includes a provision for changing the relative angular position of the pump piston and its drive shaft so as to permit a change of the fuel injection timing. The fuel injection pump receives fuel from a fuel supply pump that is constructed to deliver fuel at an rpm-dependent pressure to the injection pump supply sump.
In a known fuel injection pump of this general type, a provision exists for changing the fuel timing to shift the point of injection manually to an advanced position for the purpose of engine starting. This known fuel injection pump includes no automatic injection timing adjustment for the lower load and speed domains in which this manual adjustment takes place. In the higher load and speed domains, the injection timing is substantially load-dependent inasmuch as the link between the speed governor and the injection timer is constituted by linkage coupled to the externally settable engine control lever. One of the disadvantages of this known construction is that the adjustment of the onset of injection is load-dependent and another is that, while injection can be advanced in the lower speed and load domain, it is substantially ineffective in all the other regions.
In another known fuel injection pump, a pressure control valve permits a return of a portion of the fuel delivered by the piston to the sump or to the fuel tank so as to obtain rpm-dependent pressure control. The pump controller also actuates a valve which permits a load-dependent return flow of part of the fuel, thereby causing a load-dependent injection time adjustment. Again it is a serious disadvantage that the engine load is the only engine variable which is used to control the engine to reduce noise, toxic emissions and fuel consumption.